Fig. 1
From: The long QT syndrome family of cardiac ion channelopathies: A HuGE review
Measurement of the QT interval from the electrocardiogram (ECG). Diagram depicts the normal ECG with P-wave representing atrial activation, QRS complex representing ventricular activation and the start of ventricular contraction, and T-wave representing ventricular repolarization. The QT interval is defined as the distance from the beginning of the Q-wave to the end of the T-wave. Owing to heart rate sensitivity of the QT interval, this parameter is corrected (normalized) to heart rate (as reflected by the beat-to-beat “RR” interval), yielding the “QTc.” QT and QTc can both be expressed in msec or sec. Adapted from Liu BA, Juurlink DN. N Engl J Med 2004,1 with premission of the Massachusetts Medical Society. ©2004. All rights reserved.
